What role do NADH and FADH2 play in cellular respiration?

NADH and FADH2 play a critical role in cellular respiration by serving as electron carriers that transport high-energy electrons to the electron transport chain. During the Citric Acid Cycle, which occurs in the mitochondrial matrix, NAD+ and FAD function as coenzymes that accept electrons and protons during various enzymatic reactions. As they undergo reduction to form NADH and FADH2, these molecules capture and store energy derived from the breakdown of glucose and other substrates.

Once formed, NADH and FADH2 leave the Citric Acid Cycle and move into the inner mitochondrial membrane, where they donate their electrons to the electron transport chain. This process leads to a series of redox reactions that ultimately contribute to the production of ATP through chemiosmosis and the establishment of an electrochemical gradient across the mitochondrial membrane. The correct understanding of this role emphasizes the importance of NADH and FADH2 in linking the metabolic pathways of substrate oxidation to ATP synthesis, making them essential players in cellular energy production.